Tri-County Conference, an interim conference established to facilitate realignment. Prior to that, the school had previously participated in Division C of the Northern New Jersey Interscholastic League (NNJIL), an athletic conference consisting of public and private high schools located in Bergen County and Passaic County. With 2,478 students in grades 10-12, the school was classified by the NJSIAA for the 2019–20 school year as Group IV for most athletic competition purposes, which included schools with an enrollment of 1,060 to 5,049 students in that grade range. The football team competes in the Liberty Blue division of the North Jersey Super Football Conference, which includes 112 schools competing in 20 divisions, making it the nation's biggest football-only high school sports league. The school was classified by the NJSIAA as Group V North for football for 2022–2024. The football team won the North I Group IV state sectional championships in 1987 with a 13–7 win against Bayonne High School, finishing the season undefeated for the first time. Kennedy plays an annual Thanksgiving Day football game against Eastside High School. The days leading up to the game are filled with school spirit as the Knights and Ghosts prepare to face off. Not only do the football players practice, but so do the band, cheerleaders, and color guard of both schools. In 2011, Eastside won the 87th annual match-up between the two schools by a score of 17–12. NJ.com listed the rivalry at 21st on its 2017 list "Ranking the 31 fiercest rivalries in N.J. HS football", with Kennedy leading the series by a 43-42-7 margin. The girls' basketball team won the Group IV state championship in 1988 (defeating Neptune High School in the tournament final) and 1990 (vs. Toms River East High School). The 1988 team became the first girls team from the county to win a state title and finished the season with a 31-0 record after winning the Group IV championship game by a score of 65-55 against a Neptune team that came into the finals without a loss. The 1990 team won the Group IV title with an 80-49 win against Toms River East in the championship game and advanced to the second annual Tournament of Champions as the top seed, defeated fourth-seed Sterling High School by 75-49 in the semis and went on to win the championship with a 70-47 win against second-seeded and previously unbeaten St. John Vianney